JERUSALEM - Israel warned Hamas Tuesday it was risking "war" by failing to stop incendiary balloon attacks from Gaza, as fuel shortages in the Palestinian enclave caused by Israel's blockade caused widespread blackouts.
Israel's army earlier on Tuesday said its fighter jets had hit underground Hamas infrastructure and linked the strikes to "explosive and arson balloons launched" from Gaza.
The strikes came as visiting Egyptian security officials strove to defuse more than a week of heightened unrest that has included rocket and incendiary device attacks from Gaza and daily Israeli reprisals.
Israel's President Reuven Rivlin issued a warning to Hamas during a visit to communities near the Gaza border hit by the unrest.
"Terrorism using incendiary kites and balloons is terrorism just like any other," Rivlin said in a statement.
"Hamas should know that this is not a game. The time will come when they have to decide... if they want war they will get war," said Rivlin, who holds a largely ceremonial post in the Jewish state.
Israeli defense minister and alternate prime minister Benny Gantz said "Hamas is playing with fire," and vowed to "make certain the fire is turned back on them."
No casualties were reported in the latest Israeli airstrikes.
Israel and Hamas have fought three wars since 2008.
Despite a truce last year backed by Egypt, the UN and Qatar, Hamas and Israel clash sporadically, with Palestinian incendiary balloons or rocket or mortar fire drawing retaliatory Israeli strikes and civil sanctions.
A Hamas source told AFP the Islamists had held talks with the Egyptian delegation in Gaza on Monday before it left the territory for meetings with the Israelis and the West Bank-based Palestinian Authority.
The delegation was expected to return to Gaza after those talks were concluded, the source added.
In response to persistent balloon attacks, Israel has banned fishing off Gaza's coast and closed the Kerem Shalom goods crossing, cutting off deliveries of fuel to the territory's sole power plant.
The plant's spokesman Mohammed Thabet announced its "complete shutdown" on Tuesday after its fuel ran out.
Power had been in short supply even before the shutdown, with consumers having access to mains electricity for only around eight hours a day.
That will now be cut to just four hours a day using power supplied from the Israeli grid.
For the rest of the time, those Gazans who can afford it rely on solar panels, or generators, which also need fuel.
Hamas spokesman Fawzi Barhoum said the electricity crisis was a "crime against humanity," for which Israel must answer.
"We will work with all our force to break the siege," he said.
Gaza security sources and witnesses said Tuesday's strikes hit Hamas lookout posts at Rafah in the south of the territory and Beit Lahia in the north.
Israeli police said Tuesday that a balloon came down in the yard of a home in the town of Sderot, which is within walking distance of the Gaza border and a frequent target for attack.
It caused some damage but no casualties, a police statement said.